Customer behind this ticket has found that some tasks appear twice in business Central when we try to list completed tasks.
We think the problem is related to the sla. The two rows with the same taskid have equal values for all fields except salcompliance field.
 
I've made a simple reproducer with an user task and I was able to find the following:

In addition to the duplicate entries before in the nodeinstancelog table, we can see the duplicate tasks in the business central workbench.
 

One of them with value pending and the other one with value met in the SLA Compliance field.

I've attached a reproducer [MySpace_test_case_03365943.zip] for your reference.